You'll get a lot of opinions.
Here's mine...
I ran a 20 footer for 18 years using a single 27DP. In water all season. fishing up to 60 miles east. VHF Sonar Chartplotter, Lights. I fished at night often. I did not run a livewell.
Replaced every 5'ish years at the first hint of weakness when lowering the motor.
If I had another battery I would have had to replace 2 every five years.
That said, I'd get another 27DP ...but 2 or three years apart so they "rotate position".
also, new fuel injected four strokes start at the touch of the key. Not like old carbuerated 2 strokes ...ratatatatatatatatata....ratatatatatatataa..ship!....ratatatatata